Prior art variable pitch pulley drive systems have suffered from an inability to provide for reliable lubrication of the variable pulley mechanism. More particularly, experience has proven that users of such systems neglect to lubricate such systems when needed, and furthermore are sometimes unable to properly lubricate the system since proper lubrication of such prior art systems required the user to adjust the pulley pitch while lubricating in order to coat all axial load bearing surfaces between the pulley and its respective shaft. The nature of some applications of such variable pitch pulley drives prohibited adjustment during lubrication.
One approach to solving this problem which is followed by a number of manufacturers has been to provide a non-metallic keyed sleeve between the axially movable pulley half and the shaft which carries it. This has resulted in some degree of success, however, rapid wearout and limited peak torque capacity have continued to be problems with this approach.